RU2661582C2 - Fiber preform for a hollow turbine engine vane - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to a fiber preform for a hollow turbine engine vane, to such a hollow vane, and to a method of fabricating such a hollow vane. Invention also relates to a turbine engine and to an aircraft including such a hollow vane. Fiber preform for a hollow turbine engine vane comprises a main fiber structure obtained by three-dimensional weaving and including at least one main part, wherein the main part extends from a first link strip, includes a first main longitudinal portion suitable for forming essentially a pressure side wall of an airfoil, then includes a U-turn bend portion (45) suitable for forming, essentially, a pressure side wall (26) of an airfoil, then includes a 180°-turn bend portion, suitable for forming, essentially a leading edge or a trailing edge of the airfoil, then includes a second main longitudinal portion facing the first main longitudinal portion and suitable for forming, essentially a suction side wall of the airfoil, and terminating at a second link strip, first and second link strips are secured to each other and form a link portion of the main fiber structure, and the main longitudinal portions are spaced apart so as to form a gap between said main longitudinal portions suitable for forming a hollow in the airfoil.

EFFECT: invention provides a hollow vane having a low weight because of its hollow, which is a one-piece structure that presents very good mechanical properties.

14 cl, 12 dwg

Description

Technical field

The invention relates to a fibrous preform for a hollow blade of a gas turbine engine, to such a hollow blade and a method for manufacturing such a hollow blade. The invention also relates to a gas turbine engine and an aircraft containing such a hollow blade.

Such a preform can be used to make a hollow blade, in particular, a rear blade of a turbine or a blade for any other module in a gas turbine engine.

State of the art

Due to the high cost of fuel, significant efforts have recently been made to reduce the fuel consumption of aircraft turbojet engines. The main factor affecting fuel consumption is the weight of the aircraft and its equipment, including its turbojet engines.

Thus, over the past few years, new materials have begun to be used in aircraft turbojet engines, which have achieved significant weight reductions. This applies, in particular, to composite materials that have high mechanical strength and lower weight compared to traditionally used metal materials; Thus, the design of a new generation of turbojet engines has a large number of parts made of such composite materials.

Another approach to solving the problem of weight loss is to simplify the forms of certain parts or to exclude certain elements that are redundant. In particular, some of the previously solid elements can be hollow. This applies, in particular, to some of the blades, for example, to the blades of the rear straightening apparatus of the turbine, which are hollow in new generation gas turbine engines. In particular, this makes it possible to choose materials that can better withstand the effects of high temperatures occurring in the turbine, even if they have a slightly higher weight than traditional materials, but this does not lead to an increase in weight. In addition, such a hollow turbine blade can be used as a channel for supplying cooling air.

Under these circumstances, it is theoretically possible to combine the advantages of both methods of weight reduction by manufacturing such hollow blades from composite materials. But, nevertheless, there are few methods for manufacturing hollow parts from composite materials, they are complex and not entirely satisfactory.

In particular, one known method consists in weaving several two-dimensional fabrics, shaping them by folding and then connecting them to each other by sintering. However, this method requires the creation of a large number of fabrics that must be woven, which leads to difficulties in the joint molding of laid fabrics and to structural weaknesses of the parts that arose due to their layered structure.

Thus, there is a need to create a fibrous preform for the manufacture of a hollow blade of a gas turbine engine, such a hollow blade, as well as to develop a method of manufacturing such a hollow blade, free, at least partially, from the disadvantages inherent in the above known methods.

Disclosure of invention

The object of the invention is a fibrous preform for a hollow blade of a gas turbine engine, including a main fibrous structure obtained by three-dimensional fabric and containing at least one main part; moreover, the main part extends from the first connecting strip, comprises a first main longitudinal part suitable for forming essentially the wall of the discharge side of the aerodynamic profile, then a 180 ° rotation part suitable for forming a substantially leading edge or trailing edge of the aerodynamic profile, the second main longitudinal part facing opposite the first main longitudinal part and suitable for forming essentially the wall of the suction side of the aerodynamic profile, and the second ends second connecting strip; the first and second connecting strips are attached to each other and form the connecting part of the main fibrous structure; and the main longitudinal parts are separated from each other, forming a gap between the specified main longitudinal parts, intended for the formation of a cavity in the specified aerodynamic profile.

Such a workpiece makes it possible to obtain a hollow blade having a low weight due to its cavity, and also due to the fact that it is made of composite material.

In addition, thanks to the three-dimensional fabric, such a hollow blade is an integral structural element with very high mechanical characteristics. In addition, such a part has a reduced anisotropy, which provides increased mechanical strength regardless of the direction of action of the loads. In particular, the three-dimensional fibrous structure enables it to withstand shear forces without the risk of delamination, in contrast to, for example, sintered layers of fabric.

The use of such a blank also makes it possible to simplify the method of manufacturing hollow blades. The method may include performing only one textile step using a shuttle loom for three-dimensional weaving, currently well known in the art, which reduces the total cost and time required to make such a hollow blade. Where appropriate, it also makes it possible, during the aforementioned one textile step, to introduce other elements of the straightening apparatus into the workpiece, such as shelves or mounting flanges, which are also made as a single part with a hollow blade.

In addition, the workpiece has a shape very close to the shape of the final blade, which reduces the amount of machining required to obtain the final part. In particular, the use of such a blank provides the possibility of obtaining the final or almost final shape of the leading edge directly during the weaving step, which limits the machining to only the connecting part corresponding to the trailing edge. In addition, this method provides high mechanical characteristics of this zone, in particular, as a result of the absence of any features. In particular, it should be noted that the area of the leading edge, as a rule, is affected by more significant loads than the area of the trailing edge.

Thus, there is the possibility of creating a workpiece, part of the rotation of which forms the final or almost final shape of the trailing edge and the machining of which is required only for the leading edge.

Preferably, the connecting strips extend along the entire length of the upper along the edges of their respective main longitudinal parts.

According to the invention, the terms “longitudinal”, “transverse”, “lower”, “upper”, as well as their derivatives, are defined relative to the main directions of the blades; in addition, in relation to the workpiece, they are determined relative to the formed workpiece; the terms “axial”, “radial”, “tangential”, “internal”, “external” and their derivatives are defined relative to the main axes of the gas turbine engine and, finally, the terms “located upstream” and “located downstream” are defined relative to the direction in which the workpiece is woven.

In some embodiments, the first and second connecting strips are mutually woven with each other. Thus, the characteristics of the workpiece, and, accordingly, the resulting hollow blade is positively affected by a three-dimensional network of fibers connected to each other on the connecting part; this increases the mechanical strength of the connecting part, and therefore the leading or trailing edges of the resulting blade. In addition, the workpiece is obtained in the form of an integral part immediately after the textile stage.

In some embodiments, the 180 ° rotation portion is for forming a leading edge. The leading edge profile has a relatively large radius of curvature, which, therefore, can be relatively easily obtained using a shuttle loom.

In some embodiments, the layers of the first and second connecting stripes intersect. It also increases the strength of the connecting part.

In other embodiments, the first and second connecting stripes are not woven mutually, but simply stitched together.

In other possible embodiments, the first and second connecting strips are not mutually woven, but are bonded to each other by sintering.

In some embodiments, the preform includes a second fibrous structure obtained by weaving and configured to adhere to the edge of the main fibrous structure. This is advantageous, in particular, when a part of the workpiece is located downstream from the zone in which the shuttle of the loom rotates 180 °, and this part is thus impossible to weave together with the rest of the workpiece during the same weaving step. This applies, in particular, to any part of the workpiece located downstream of the rotation part of the main part of the main fibrous structure and intended, for example, to form part of the shelves or mounting flanges.

In some embodiments, a second fibrous structure is obtained using three-dimensional textile.

In other embodiments, the second fibrous structure comprises one or more two-dimensional layers.

In some embodiments, a second fibrous structure is attached to the edge by crosslinking the base of the fibrous structure.

In some embodiments, a second fibrous structure is attached to the edge by a base of the fibrous structure by sintering.

In some embodiments, a second fibrous structure is attached to the edge by a base of the fibrous structure by simultaneously injecting the matrix.

In some embodiments of the invention, at least one of the fibrous structures comprises at least one radial part extending from the lower or upper edge of one of the main longitudinal parts of the main part and intended to form a shelf or mounting flange. As mentioned above, this makes it possible to create a shelf or a mounting flange in the form of an integral part, and makes it possible to do this during the same stage of manufacturing a hollow blade. Thus, due to this, the mechanical strength of the assembly and, in particular, the line connecting the blades with the shelf or flange is increased. In addition, this makes it possible to reduce the number of required parts, in particular fasteners, which reduces the weight and cost of the node as a whole.

In some embodiments, said radial portion extends along the entire lower or upper edge of said main longitudinal portion.

In some embodiments, at least one of the fibrous structures also comprises at least one additional longitudinal portion extending from an edge of said radial portion to form a mounting flange.

In some embodiments, at least one of the fibrous structures comprises an overlapping portion that, when the fibrous structure is in a planar state, is located upstream of at least a portion of the connecting portion of the main portion, and remains between said overlapping portion and the connecting portion gap. This gap can be cut out in fibrous structures after they are obtained during the weaving step. This makes it possible to create a part of the shelf or mounting flange protruding beyond the plane of the chord of the hollow blade. In addition, this makes it possible to create overlapping zones in which various sheets or fibrous structures overlap each other after molding, thereby providing better adhesion and increased strength to the final shelf or mounting flange.

In some embodiments, the implementation of the connecting part of the main part has a smaller width in its lower and / or upper part than in the middle part. The smaller width of the connecting part in the lower or upper part serves to reduce the volume of the required machining in these zones, which is of great importance, since we are talking about connecting the front or rear edges of the blades with the shelf. Conversely, the width of the connecting part in its middle part between the connection zones can be larger, for example, to increase strength, since the restrictions for this zone are not so strict.

In some embodiments, the yarns used to weave the preform are fibers of oxide, carbon, or carbide ceramic, and preferably alumina, mullite, silicon dioxide, zirconia, silicon carbide, or a mixture thereof. However, other types of fibers can be used, for example, fiberglass or Kevlar fiber.

In some embodiments, the fabric used for three-dimensional weaving of the preform, in particular the connecting part, may be a three-dimensional interlock type. However, the weaving of the outer surfaces of the preform may be essentially two-dimensional, for example, a satin type.

The object of the invention is also a hollow blade made in the form of an integral part made of a composite material from a fiber preform in accordance with any of the above-described embodiments, wherein said preform is molded in a mold and enclosed in a matrix.

In some embodiments, the hollow blade is a rear turbine blade.

In other embodiments, said hollow blade is a nozzle blade. It can be, in particular, an output guide vane.

In some embodiments, the matrix is made of oxide or carbide ceramic. Preferably, the matrix is made of alumina, mullite, silicon dioxide, zirconia, silicon carbide, or a mixture thereof. Preferably, the matrix is microporous. However, it can also be ceramic, based on boride or nitride. It can also be an organic matrix, for example, an epoxy type.

A subject of the invention is also a gas turbine engine comprising a hollow blade according to any of the above embodiments.

The object of the invention is also an aircraft containing the above gas turbine engine.

And finally, an object of the invention is a method for manufacturing a hollow blade, comprising at least the step of weaving and cutting a fibrous preform according to any of the above embodiments.

The specified method makes it possible to obtain a draft part having essentially the shape required for the final part, possibly containing a shelf and mounting flanges, with the exception of the bulge located upstream formed by the edge of the connecting part of the workpiece; this bulge is subsequently machined to produce a leading or trailing edge of the final part.

In some embodiments, the weaving step is performed using a three-dimensional weaving loom with a bundle of warp yarns and at least one shuttle capable of inserting a weft yarn between warp yarns; moreover, the shuttle performs successive back-and-forth movements, starting from the connection zone, moving along the first main longitudinal zone, performing a 180 ° turn in the turning zone, moving along the second main longitudinal zone opposite the first main longitudinal zone, and returning to the connection zone, wherein each round-trip can be performed in that direction or in the opposite direction; and the thread / threads of the weft yarn interacts / interacts with the warp threads, forming a three-dimensional weaving in the connection zone, in the first and second main longitudinal zones and in the turning zone. With the help of a shuttle loom, which makes it possible to carry out this method by weaving with a rotation of 180 °, it is possible to obtain a hollow workpiece with only one connecting part at one of its edges, while the textile at its other edge forms the desired shape.

In some embodiments, the method further includes the steps of: cutting a fiber preform; folding and forming the fiber preform in a mold having the shape of the desired draft part; place the insert in the gap between the two main longitudinal parts; injection and hardening, preferably by drying, of the matrix around the fibrous preform to obtain a rough part; the insert is removed, sintered and machined the connecting portion of the draft part corresponding to the connecting part of the fiber preform to obtain the leading or trailing edge of the final part.

In some embodiments, the implementation of the hollow blade is obtained from the workpiece according to the technology of injection molding of material (LFM), known in the art. With this technology, the injected liquid is either a pre-ceramic polymer, possibly with a powder filler, or a sol-gel, possibly also with a powder filler, or some other suspension, preferably a mixture of a powder, an organic binder and a solvent.

In other embodiments, the implementation of the hollow blade is made from the workpiece using the technology of "polyflex" (Polyflex). With this method, the fiber preform is placed in position on a fixture having a surface whose profile shape corresponds to the profile of the resulting finished part. Then the preform is coated with a flexible impermeable membrane, and the matrix is injected into the space between the membrane and the preform. Isostatic pressure is applied to the other side of the membrane using a fluid. The fluid causes the binder to penetrate into the space between the fibers and maintains pressure during the drying of the matrix.

In other embodiments, when the preform contains a second fibrous structure that is not attached to the main fibrous structure before injection and curing, the second fibrous structure is placed in the same mold with the main fibrous structure, a hollow blade is obtained from the preform by co-injection.

In some embodiments, the step of machining the connecting portion of the draft part corresponding to the connecting portion of the fiber preform includes sharpening said connecting portion to provide a trailing edge.

In some embodiments, this method does not include the step of machining a rotation part of a draft part corresponding to a rotation part of a workpiece.

The above features and advantages, as well as other characteristics, are disclosed in the following detailed description of embodiments of the preform and the implementation of the method according to the invention. A detailed description of the invention is given with reference to the drawings.

Brief Description of the Drawings

The drawings are schematic and primarily serve to explain the principles of the invention.

In FIG. 1 shows a gas turbine engine according to the invention, a sectional view;

in FIG. 2 - rear straightening apparatus of the turbine, perspective view;

in FIG. 3 - hollow shoulder blade, sectional view;

in FIG. 4 - the main part of the workpiece according to the first embodiment, a perspective view;

in FIG. 5 is a diagram showing a fiber weaving direction for this main part of a preform;

in FIG. 6 is an example of a fiber weaving direction for this main part of a preform;

in FIG. 7 is a part of a workpiece in a flat state according to a first embodiment;

in FIG. 8 - the same workpiece after molding;

in FIG. 9 - the rear edge of the workpiece after molding, an enlarged view;

in FIG. 10 is a draft detail obtained from the workpiece, a perspective view;

in FIG. 11 - final hollow turbine blade obtained after machining a rough part, perspective view;

in FIG. 12 is a part of a workpiece in a flat state according to a second embodiment.

Embodiments of the invention

In order to concretize the invention, the following is a description of an example of a workpiece and a manufacturing method with reference to the drawings. It should be borne in mind that the invention is not limited to these examples.

In FIG. 1 shows a turbofan engine 1 according to the invention, a sectional view along a vertical plane containing its longitudinal axis A. From the air flow direction upstream to the downstream direction, this engine contains: fan 2, low pressure compressor 3, high pressure compressor 4 , a combustion chamber 5, a high-pressure turbine 6 and a low-pressure turbine 7. This engine also includes a rear turbine straightener 10 installed in the primary air circuit at the outlet of the low-pressure turbine 7.

In FIG. 2 shows such a rear turbine straightener 10, a perspective view. This apparatus comprises an inner sleeve 11 and an outer rim 12, radially connected to each other by the blades 20 of the rectifier, usually called the rear blades of the turbine.

In FIG. 11 is a perspective view showing an example of a blade 20 according to the invention, in particular a rear blade of a turbine. Such a blade includes an aerodynamic profile 21, a lower flange 22, an upper flange 23, and also the lower and upper mounting flanges 24 and 25. Part of the aerodynamic profile 21 mainly performs the aerodynamic function of the blades 20; shelves 22 and 23 serve as internal and external walls for the air channel, and their surface is smooth and aerodynamic; mounting flanges 24 and 25 serve, respectively, for connecting the blades 20 to the inner sleeve 11 and to the outer rim 12.

The aerodynamic profile 21 of such a rear turbine blade 20 is shown in section in FIG. 3. It includes a pressure side wall 26 (trough) and a suction side wall (back) 27, which are connected to each other on one side by a front edge 28, and a trailing edge 29 on the other side; these walls 26 and 27 of the discharge side and the suction side form an internal cavity 30 forming a hollow blade. In this example, said blade cavity 30 should remain empty in order to reduce the weight of the straightening apparatus. However, in other examples, in particular for other types of this part, such an internal cavity can be used for the passage or passage of air. In addition, the leading edge 28 and trailing edge 29 define a plane P of the chord.

In FIG. 4 is a diagram showing the main part 41 of the woven fiber preform 40, which is used to make such a blade 20. In these figures, the direction of the weft yarn is represented by the arrow T, i.e. yarn weft runs from right to left, and the direction of the warp threads is shown by arrow C. However, patterns are possible in which weaving will be from the other edge and in the opposite direction.

In this embodiment, the preform 40 is made by three-dimensional weaving of alumina fibers by three-dimensional interlocking weaving.

This main part 41 of the workpiece 40 contains a mainly fibrous structure in the form of a loop, containing (one after the other around the loop) a connecting part 44, a first main longitudinal part 46, a rotation part 45, and a second main longitudinal part 47. Thus it is clear that the main longitudinal parts 46 and 47 form the discharge side wall 26 and the suction side wall 27 of the aerodynamic profile 21, the 180 ° rotation portion 45 forms the leading edge 28, and the connecting part 44 forms the trailing edge 29.

FIG. 5 and 6 explain how the weaving of this main part 41 of the workpiece 40 is carried out. The weaving of such a workpiece can be done using a three-dimensional textile loom having at least one shuttle extending the weft yarn and able to move freely between the warp yarns. In such a loop, the shuttle moves in such a way as to form a round-trip path U between the indicated connection zone 44a in which the connecting part 44 is formed and the specified rotation zone 45a in which the rotation part 45 is created.

Thus, with each round-trip, the shuttle begins to move from the connection zone 44a, passes through the first main longitudinal zone 46a, in which the first main longitudinal part 46 is formed, then through the rotation zone 45a, where it rotates 180 °, and returns to the connection zone 44a passing through the second main longitudinal zone 47a in which the second main longitudinal part 47 is formed.

Each round-trip U can be performed in the same direction or in opposite directions, i.e. the direction of movement may change from a clockwise direction to a counterclockwise direction.

As a result of the sequence of such U back-and-forth movements, the main part 41 of the workpiece 40 is formed with a predetermined layer thickness, in which, naturally, the layer thickness in the connecting part 44 is larger due to the fact that the shuttle more often passes through the connection zone 44a. For this, we can assume that the connecting part 44 is made of a first connecting strip 44p and a second connecting strip 44q, which lie on top of each other and are connected to each other by means of textile. However, this is only a virtual concept, since there is no physical border that separates these two bands, and the connecting part 44 is a single tape, uniformly interconnected by three-dimensional weaving.

In FIG. 6 shows an example of a trajectory V along which the shuttle can move to form such a main part 41 of the workpiece 40. In this example, the shuttle moves back and forth, each time changing the direction of its movement. It should also be noted that the shuttle forces the layers in the connection of the connecting part 44 to the main longitudinal parts 46 and 47 to intersect. Thus, in this example, the main part 41 of the workpiece 40 has a thickness equal to three threads of the weft yarn, and a thickness equal to six layers on its connecting part 44.

Of course, it is understood that FIG. 5 and 6 show the trajectory along which the shuttle passes in one given plane of the workpiece, however, the interlacing of the fibers of the workpiece in another plane is similar, resulting in a three-dimensional textile, in particular a three-dimensional textile of interlock type, with a change in the local position of the threads between each plane weaving. Thus, each weaving plane can have its own shuttle, and weaving in different planes of the workpiece can be done simultaneously; otherwise, in a different configuration, the same shuttle weaves sequentially in one plane after another.

So, after the weaving operation, the main part 41 of the workpiece is obtained in the form of a single piece with three-dimensional weaving in each of its parts, including the connecting part, as well as the rotation part 45, the shape of which immediately after the weaving stage essentially corresponds to the desired shape of the leading edge.

In FIG. 7 shows a flat blank 40 cut from a piece. FIG. 8 shows this preform 40 after molding. In these figures, for the sake of clarity, only the front sheets of the blank 40 are shown in cut out form, however, it should be borne in mind that the blank 40 also has other sheets lying behind the sheets shown and having a substantially similar shape.

The blank 40 comprises a main part 41, the first main longitudinal part 46 of which is located between the connecting part 44 and the rotation part 45, and extends, respectively, along the upper and lower ends of the first main longitudinal part 46.

The blank 40 also includes an upper front sheet 48s and a lower front sheet 48i, which are woven independently and respectively attached to the upper and lower edges of the main part 41, mainly the first main longitudinal part 46. In this example, these additional fibrous structures 48s and 48i attached to the body 41 by stitching. There is also the possibility of placing these sheets in a form and attaching them to the main part by means of joint injection followed by sintering.

The lower front sheet 48i comprises a portion 52, called a lower radial portion, which extends from the lower edge of the main longitudinal portion 46 to the lower edge of the workpiece 40. This lower radial portion 52 also includes an upstream overlapping portion 52m that extends around and extends into the portion, located upstream of the connecting portion 44. The lower radial portion 52 also has a downstream overlapping portion 52v extending around and partially extending downstream of the rotation portion 45.

When forming the workpiece 40, this radial part 52 is folded into a radial position, so as to form part of the discharge side of the lower shelf 22.

This radial portion 52 also extends upstream of the upstream supplementary longitudinal portion 54m and downstream of the downstream supplementary longitudinal portion 54v. These parts can be folded in the longitudinal direction, so as to form the lower mounting flanges 24.

Similarly, the upper front sheet 48s comprises a portion 53 called the upper radial portion, which extends from the upper edge of the main longitudinal portion 46 to the upper edge of the workpiece 40. This upper radial portion 53 has overlapping portions 53m and 53v located upstream and downstream. This upper radial portion 53 can be folded into a radial position, so as to form part of the discharge side of the upper shelf 23.

This upper radial part 53 also continues downstream by a sequence of intermediate parts 59 leading to an additional downstream longitudinal part 55v located downstream and an upstream additional longitudinal part 55m upstream. These parts can be folded in the longitudinal direction, so as to form the upper mounting flanges 25.

The preform 40 can be wetted to make it softer and easier to shift the fibers from their location. Then the workpiece is placed in a mold whose inner space corresponds to the desired shape of the workpiece 40.

The process of forming the trailing edge of the blank 40 is described in more detail in FIG. 9. In this drawing, superimposed on each other shows the shape of the workpiece 40 (dotted line) and the shape of the final part 20 (solid lines). During molding, the main longitudinal parts 46 and 47 are separated by a gap 50. Then an insert is introduced into the gap 50 so that the matrix does not fill it during injection and setting, thus allowing a cavity 30 to be created in the aerodynamic profile.

At the trailing edge 29, the main longitudinal parts 46 and 47 converge uniformly, forming the connecting part 44. The molding is performed so that the trailing edge 29 of the final part 20 is on the median plane 44 'of the connecting part 44.

After shaping by molding, the preform 40 is dried, so as to make it stiff, while continuing to hold it in the molding tool. Then, the workpiece 40 is placed in a mold, the dimensions of which correspond to the desired draft part 60 of the blade, and the injection matrix (in particular, porous alumina) is injected into the specified mold. Such injection can be performed, for example, by injection molding technology of the material (LFM). At the end of this step, after drying and removing the insert, a rough blade part 60 made of a composite material is obtained containing a woven blank 40 of alumina fibers embedded in an alumina matrix.

As shown in FIG. 10, the draft part 60 already has the required leading edge 28, shelves 22 and 23, and the mounting flanges 24 and 25. On the contrary, the aerodynamic profile 61 of the draft part 60 contains a bulge 64 due to the far edge of the connecting portion obtained from the connecting part 44. This bulge as also seen in FIG. 9, it is necessary to remove by machining to obtain the final blade 21. This machining includes cutting the bulge 64 and sharpening the trailing edge on both sides of the median plane 44 'of the connecting portion 44.

To facilitate the machining of the joints of the aerodynamic profile 21 with the shelves 22 and 23 and to prevent weakening of the blade structure, the connecting part 44 has a small width of approximately 5 mm at the upper and lower edges; in the center of the aerodynamic profile 21, its width is greater and is about 10 mm.

In addition, during finishing processing of the blade 20, other finishing steps, including machining steps, can be performed.

In FIG. 12 shows yet another possible embodiment of the workpiece 140, in which weaving on large parts of the upper and lower front sheets 48s and 48i of the above-described workpiece example is performed while weaving the main part 141 of the workpiece during the general weaving step.

The need to force the shuttle to rotate 180 ° in the rotation zone in order to obtain the desired shape of the leading edge during the weaving stage means that during the same weaving stage it is impossible to weave the parts of the workpiece located directly downstream from the turning zone. However, before and after this turning zone, the shuttle can rotate 180 ° further downstream in order to weave most of the upper and lower sheets during the same stage.

Thus, in this second example, the main textile step ends with the creation of the main fibrous structure as a single element containing the main part 141 with its first and second main longitudinal parts 146 between the connecting part 144 and the turning part 145, the lower radial part 152, the upper radial part 153 and additional longitudinal parts 154m and 155m located upstream, similar to parts of the same type in the first embodiment.

The main fibrous structure of the preform 140 also has lower and upper parts 157i and 157s located downstream, extending downstream from the rotation portion 145, respectively, downstream and above it. It should be recalled that in FIG. 12 only front sheets are shown, however, the rear sheets may contain the same parts, and the shuttle may, for example, weave the front parts when moving in one direction, and the rear parts when moving in the opposite direction.

Weaving of the lower and upper downstream sheets 158i and 158s is also carried out separately, and the sheets are secured by sewing to the upper edges of the lower downstream parts 157i and the lower edges of the upper downstream parts 157s, respectively. Due to these added fibrous structures, the preform 140 comprises downstream additional longitudinal parts 154v and 155v, similar to those in the first embodiment.

In addition, it should be noted that the main fibrous structure of the workpiece 140 also contains upstream overlapping parts 152m and 153m extending around the connecting part 144, respectively, above and below, which are located partially upstream of the specified connecting part, with a gap of 149 cut in a fibrous structure and separating these overlapping parts 152m and 153m from the connecting part 144. The cutout forming the gap 149 can be made, in particular, by a jet of water under pressure or a laser beam.

The embodiments or embodiments disclosed according to the invention are given only as non-limiting examples, and one skilled in the art will be able to easily modify these options or create new ones in light of this disclosure without changing the essence of the invention.

In addition, various features of these embodiments or embodiments may be used individually or in combination with each other. When used in combination with each other, these features can be combined, as described above, or otherwise, and the invention is not limited to any particular combinations disclosed. In particular, unless otherwise indicated, a feature disclosed with reference to a specific embodiment or embodiment of the invention may likewise be used in any other embodiment or embodiment.

Claims (25)

1. A fibrous preform for a hollow blade of a gas turbine engine, including a main fibrous structure obtained by three-dimensional fabric and containing at least one main part (41); moreover, the main part (41) extends from the first connecting strip (44p), contains the first main longitudinal part (46), suitable for forming essentially the wall (26) of the discharge side of the aerodynamic profile (21), then the rotation part (45) 180 °, suitable for forming essentially the leading edge (28) or trailing edge (29) of the aerodynamic profile, then the second main longitudinal part (47) facing opposite the first main longitudinal part (46) and suitable for forming essentially walls (27) of the aerodynamic suction side profile (21), and ends with a second connecting strip (44q); the first and second connecting strips (44p, 44q) are attached to each other and form the connecting part (44) of the main fibrous structure; and the main longitudinal parts (46, 47) are separated from each other, forming a gap (50) between the specified main longitudinal parts (46, 47), designed to form a cavity (30) in the specified aerodynamic profile. 2. The fiber preform according to claim 1, in which the first and second connecting strips (44p, 44q) are mutually woven with each other. 3. The fibrous preform according to claim 1 or 2, further comprising a second fibrous structure (48i) obtained by weaving and configured to attach to the edge of the main fibrous structure (41). 4. The fibrous preform according to claim 1, in which at least one of the fibrous structures (48i) contains at least one radial part (52) extending from the lower or upper edge of one of the main longitudinal parts (46) of the main part (41 ) and designed to form a shelf (22) or a mounting flange. 5. The fibrous preform according to claim 4, in which at least one of the fibrous structures contains an overlapping part (152m), which, when the fibrous structure is in a flat state, is located upstream of at least part of the connecting part (144 ) of the main part (141), and a gap (149) remains between the specified overlapping part (152m) and the connecting part (144). 6. The fibrous preform according to claim 1, in which the connecting part (44) of the main part (41) has a smaller width in its lower and / or upper part than in the middle part. 7. Hollow blade, in particular the rear blade of the turbine, characterized in that it is made in the form of an integral part of a composite material from a fibrous preform (40) according to any one of paragraphs. 1-6, and the specified preform (40) is molded in a mold and enclosed in a matrix. 8. A hollow blade according to claim 7, in which the fiber preform (40) is made of fibers of oxide, carbon or carbide ceramic and, preferably, of aluminum oxide, mullite, silicon dioxide, zirconia, silicon carbide, or a mixture thereof. 9. The hollow blade according to claim 7 or 8, in which the matrix is made of oxide, carbide or nitride ceramic or is an organic epoxy type, preferably made of alumina, mullite, silicon dioxide, zirconium dioxide, nitride or silicon carbide or a mixture thereof . 10. Gas turbine engine, characterized in that it contains a hollow blade (20) according to any one of paragraphs. 7-9. 11. A method of manufacturing a hollow blade, comprising at least the step of weaving a fibrous preform (40) according to any one of paragraphs. 1-6. 12. The method of claim 11, wherein the weaving step is performed using a three-dimensional weaving loom with a bundle of warp yarns and at least one shuttle capable of inserting a weft yarn between warp yarns; moreover, the shuttle sequentially moves (U) back and forth starting from the connection zone (44a), moving along the first main longitudinal zone (46a), performing a 180 ° turn in the turning zone (45a), moving along the second main longitudinal zone (47a) located opposite the first main longitudinal zone (46a), and returning to the connection zone (44a), each movement (U) back and forth can be performed in this direction or in the opposite direction; and the thread / threads of the weft yarn interacts / interacts with the warp threads, forming a three-dimensional weaving in the joint zone (44a), in the first and second main longitudinal zones (46a, 47a) and in the turning zone (45a). 13. The method according to p. 11 or 12, further comprising stages in which: fibrous preform is cut out (40); folding and forming the fiber preform (40) in a mold having the shape of the desired draft part (60); place the insert in the gap (50) between the two main longitudinal parts (46, 47); pumping and hardening the matrix around the fibrous preform (40) to obtain a rough part (60); removing the insert; and machining the connecting portion (64) of the draft part (60) corresponding to the connecting part (44) of the fiber preform (40) to obtain the leading or trailing edge (28, 29) of the final part (20). 14. The method according to p. 13, in which the step of machining the connecting portion of the draft part (60) corresponding to the connecting portion (44) of the fiber preform (40) essentially includes sharpening said connecting portion (64) to obtain a trailing edge (29).

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